Superionic Diffusion Through Frustrated Energy Landscape

Solid-state materials with extremely high ionic diffusion are necessary to many technologies including all-solid-state Li-ion batteries. Despite the strong efforts made towards the search for crystal structures leading high lithium diffusion, only a handful crystalline structure families have been reported as Li superionic conductors.
In this work, we demonstrate that LiTi2(PS4)3, or LTPS, shows exceptional Li-ion diffusion an order of magnitude higher than current state-of-the-art superionic conductors. By means of extensive theoretical studies through ab initio molecular dynamics (backed up by several experimental characterization), we rationalize the exceptional performances of this new superionic conductor through the concept of frustrated energy landscape. The absence of regular and undistorted sites for Li leads to low diffusion energy barrier as well as an exceptional pre-factor.
Our work not only sheds light on a new family of superionic conductors but offers a new design principle for discovering new ones.